1. Field of the Invention
The present invention relates to a device for automatically controlling audio volume based on vehicle speed and a method for operating the same, and more particularly to a device for automatically controlling audio volume based on vehicle speed and a method for operating the same, wherein the volume of a car audio device is automatically controlled in such a manner that the car audio volume is corrected to keep the car audio volume at a uniform level relative to noise occurring at a level proportional to vehicle speed.
2. Description of the Related Art
With reference to FIG. 1, a conventional device for controlling audio volume in a vehicle is described as follows. FIG. 1 shows the inside space of a general vehicle equipped with an embedded car audio device including a speaker.
Car audio refers to a device designed to allow users in a specified space, the inside space of a car, to listen to powerful sound by improving the performance of audio elements such as a head unit, an amplifier and a speaker, compared to a general home audio system.
The car audio system is classified into two types, one type being a stock type product that is installed directly by a car manufacturer at the time of manufacturing the car (called a “car stereo”) and the other being an upgrade or aftermarket type product that is selected by customers (called a “car audio”). The car stereo is an integrated audio system that integrates a tuner for listening to the radio, a deck for listening to a cassette tape and an amplifier into a single unit. On the other hand, the aftermarket car audio system installs an amplifier, a tuner and a deck separately from each other as in a home audio system so as to provide more powerful sound.
Sound generated from a head unit including a tuner, a cassette deck and an amplifier is outputted through a speaker system installed in the inside space of a vehicle, where the speaker system is divided into a front speaker, a rear speaker and a sub woofer according to their installation location.
Such a car audio system has come into wide use in most vehicles since it allows a user inside a moving vehicle to enjoy original sound almost as vivid as home audio, so that a driver can listen to music, a radio broadcast, etc., while the vehicle is moving.
However, as a vehicle travels at high speed, running noise of the vehicle is produced by friction between air and the moving vehicle body and an engine rotating at high speed. That is, as the vehicle speed is increased, noise such as noise due to friction against wind, the vehicle's engine sound and frictional sound of the vehicle's tires is increased in proportion to the vehicle speed, whereas sound produced in the vehicle is relatively weakened due to the increased external noise.
Accordingly, after the volume has been turned up at high traveling speed, since sound outputted from a speaker S of a car audio device is weak, the volume must be turned down when the vehicle travels at low speed or when it is parked or stopped. In particular, in the conventional car audio device, if a driver desires to keep the speaker volume at a uniform level, the driver must manually manipulate a volume control button B to control the volume, which causes inconvenience of manipulation.
In order to manually control the volume, it is necessary for a driver wearing a seat belt to bend his or her upper body, which makes it difficult for the driver to secure his or her field of vision and thus decreases driving concentration, consequently increasing the risk of an accident. In addition, if the volume is not controlled suitably, the driver easily experiences discomfort at his or her ears when he or she listens to the radio or music reproduced through the car audio device, which may reduce the device's utilization rate.